JPH0981084A - Display device and display control method for screen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a display device having a high-speed display and low power consumption by shortening a display screen updating time and also reducing a data transferring amount and a display signal processing as the whole of a system in the middle of scrroling picture information. SOLUTION: In a display device displaying a picture by display data on a picture display means, at the time of a scrrol display, the display data being the object of the scrrol display are applied by being thinned and also means 5-7 controlling the applied display data so as to display them in the prescribed part area of the picture display means are provided. Consequently, since the display screen updating time is shortened at the time of the scrrol display and a comfortable user-interface can be provided and also the data transferring amount and the display signal processing are reduced, the display device having the high-speed display and low power consumption is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device and a screen display control method capable of saving power when performing scroll display.

[0002]

2. Description of the Related Art Generally, a display device capable of displaying an image displays a signal sent from a signal source such as a TV camera on a display screen as it is, or a semiconductor such as a personal computer on a display device or a signal source. A display signal holding unit such as a memory is provided, and an image is displayed on the display screen by using display signals read from the holding unit at a constant cycle.

In any of these display devices, since the display signal supplied to the display device has a constant cycle in either case, the power consumption of the display device is irrespective of the contents of the display signal.
Almost constant. That is, the power consumption of the display device cannot be significantly reduced depending on the display signal and the display content.

Now, consider a case where a signal source side (system side) has a memory and a signal held in the memory is transmitted to a display device for display, such as a personal computer.
FIG. 8 is a block diagram showing a system configuration example of a conventional general personal computer.

In the configuration example of FIG. 8, the display signal supplied to the display device 81 is held in the image memory (VRAM) 82, and the display signal is displayed by the display controller (D).
VGA (Video) by ISP-CONT) 80
The display signal is read out at a constant cycle in conformity with a display standard such as Graphics Array).

The display signal read out at a constant cycle is supplied to the display device 81 through the display signal bus 83. In the case of a personal computer, it has a microprocessor (CPU) 84 that is the center for arithmetic processing and control.
In order to retain the memory of the program executed by 84, R
An OM (Read Only Memory) 85 and a RAM (Random Access Memory) 86 are provided and allocated to the main memory address space of the CPU 84. Also, as an external storage device, a HDD (hard disk device) 87 or FDD
A device such as a (floppy disk device) 88 is provided so that text, image data, programs and the like can be stored and used.

In the case of displaying an image on a personal computer, it is general to write the data to be displayed in the VRAM 82, read it and give it to the display device 81. As can be seen from the configuration example of FIG. RAM86 and H
When data is taken in from a storage device such as the DD (HDC) 87 or FDD (FDC) 88, it is necessary to perform it through DISP-CONT.

FIG. 9 shows a block diagram of a general VRAM. The VRAM 82 is a cell array that holds target data for image display, a control element, and a parallel I / O that is an input / output unit for performing parallel input / output.
(W1 / IO1 to W4 / IO4) and a serial I / O (SI) which is an input / output unit for performing serial input / output.
O1 to SIO4) and the input / output between the outside and the cell array including the control signal is performed by the parallel I / O.
Via parallel data via. Further, for image data, input / output between the outside and the cell array can be performed as serial data via the serial I / O.

The VRAM 82 is controlled by DISP-CONT.
By 86. And DISP-CONT8
6 normally updates the contents of the VRAM 82.
Parallel I / O in FIG. 9 (W1 / IO1 to W4 / IO
4) and display signals supplied to the display device 81 are controlled through serial I / O (SIO1 to SIO4).

In general, in the VRAM 82, parallel I / O is provided as compared with serial I / O for performing serial input / output.
Since the operation speed of 1 is slow by one digit, the operation speed of the VRAM 82 when performing parallel input / output processing is about one digit slower than when performing serial input / output processing. However, since the serial I / O is provided for display, it cannot normally be used for rewriting data contents. That is, in the display device, it is necessary to receive the image signal in accordance with the scanning speed of the screen, and when rewriting the data content of the VRAM 82 or scrolling the display screen,
Since it is necessary to rewrite a huge amount of data in the VRAM, it can be seen that it takes a very long time to update the display data in the VRAM, that is, the display image displayed on the display device.

In particular, in recent years, the display has been increasing in definition and the capacity of VRAM has been increasing in order to handle high definition images.
Since it takes more and more time to update the RAM data, there is a problem that it is not possible to realize a comfortable usage environment (user interface) for updating the display screen at a fast speed.

[0012] In order to avoid this, systems such as personal computers and word processors (word processor devices) are becoming more compact in order to save space and portability, and liquid crystal display devices are indispensable as the display device. However, the slow operation speed of the liquid crystal display device poses a problem. Further, in a compact personal computer or word processor, since the power source is a battery, further power saving is required from the viewpoint of its weight and storage space.

[0013]

In a liquid crystal display device, one of the key technologies for power saving is the use of a liquid crystal display device (LCD) using a ferroelectric liquid crystal (FLC). Liquid crystal display device (FLC) using ferroelectric liquid crystal
-In the case of (LCD), since the screen itself of the display device has a memory property (image storage characteristic), it is not necessary to continue to give a display signal when the display is good in a still image state, and the display content changes. In this case, the display signal is transmitted only when the display is performed, and the display is performed. Since the drive energy is unnecessary during the period in which the display state is not changed, there is a sufficient base for saving the power energy.

That is, except for a storage cathode ray tube (a cathode ray tube (CRT) using a phosphor having a high afterglow) and the like, a display device usually used for a display always gives a display signal to perform display scanning. Otherwise, the image will disappear.

However, assuming that the screen itself of the display device has a memory property (image storage characteristic), a display signal is sent from the system side such as a personal computer at a constant cycle like a general CRT. It is not necessary to continue to give a display, and it is also possible to transmit a display signal and display only when the display content is changed.

A liquid crystal display device (LCD) using a ferroelectric liquid crystal (FLC) is widely known as a display device having a memory property on the screen of the display device. However, a liquid crystal display device (FLC-L) using this ferroelectric liquid crystal
In the case of CD), the slow operation speed has closed the way of using it for portable personal computers.

That is, the operating characteristics of the FLC-LCD are as shown in FIG. 4, and have hysteresis characteristics.
When the applied voltage is increased in the positive direction from zero voltage in the state where the amount of transmitted light is 0%, a certain voltage level (+ Vth;
When the amount of transmitted light increases when <+ Vth) is reached and the applied voltage is further increased in the positive direction, a certain voltage level (+
When the voltage reaches Vth), the amount of transmitted light increases, and at a certain voltage level (+ Vsat; however, 0 <+ Vth <+ Vsat), the amount of transmitted light becomes maximum, and in the saturated state, the amount of transmitted light no longer changes. This is the ON state of the pixel.

Next, from this state, the applied voltage is changed in the negative direction. Then, even when the voltage becomes zero, the maximum amount of transmitted light continues, and when the voltage is further changed in the negative direction, a certain voltage level (-Vth; where 0> -V
th), the amount of transmitted light decreases, and when the applied voltage is further decreased in the negative direction, a certain voltage level (-Vsat
However, when 0>-Vth> -Vsat), the transmitted light amount becomes the minimum, and in the saturated state, the transmitted light amount no longer changes. This is the OFF state of the pixel.

Then, from this state, when the applied voltage is increased in the positive direction this time, the amount of transmitted light does not change even when the voltage reaches zero, and the applied voltage is further increased in the positive direction and a certain voltage level ( + Vth; However, when the amount of transmitted light increases when 0 <+ Vth) is reached, and when the applied voltage is further increased in the positive direction, the amount of transmitted light increases when a certain voltage level (+ Vth) is reached and a certain voltage is reached. Level (+ Vsat; However,
When 0 <+ Vth <+ Vsat), the amount of transmitted light becomes maximum.

In other words, in the FLC-LCD, it is necessary to apply a voltage of + Vsat or higher to turn the pixel on, and to turn the pixel off, -Vsat.
The following voltages need to be applied. However, after applying the voltage, the state of the pixel is maintained as it is even if the voltage is set to zero. This is the memory property in FLC-LCD.

In the FLC-LCD, the time required to change the display content of the display is determined by the liquid crystal material, and the value is about several μs per line of the display image.
˜Several 10 μs. When driving the FLC-LCD, a driving signal as shown in FIG. 5 is used. 5A shows the waveform of the scan electrode drive signal, FIG. 5B shows the OFF waveform, FIG. 5C shows the ON waveform, and FIG. 5D shows the OFF waveform.
Pixel (off pixel; black pixel) potential, (e) is on
This is the potential of a pixel (on pixel; white pixel).

When the signal power supply uses a bipolar pulse signal having two polarities of + and −, the waveform for turning the pixel on and the waveform for turning the pixel off are FL shown in FIG.
Due to the characteristics of the C-LCD, when the OFF display of the pixel is performed, a pulse having a positive polarity first and then a pulse having a negative polarity are used ((d) in FIG. 5), so that the voltage applied at the end is -Vsat or higher, and the pixel O
When N display is performed, a pulse having a negative polarity first and then a pulse having a positive polarity is used ((e) in FIG. 5) so that the voltage finally applied is equal to or higher than + Vsat. .

Therefore, from the above, in the case of the display scanning of 2 fields and 1 frame, the pixel state is set to O.
In order to change from the N state to the OFF state, or vice versa, such a voltage applying operation must be performed for each field. Therefore, it is sufficient to change the voltage. It can be seen that it requires double the writing time.

In other words, when the display image becomes finer and the number of display lines increases, the rewriting time of the display image becomes correspondingly long, and the system side in the case of updating a large amount of display data. Along with the increase in the VRAM rewriting time, there arises a problem that a comfortable usage environment (user interface) cannot be realized.

The present invention has been made in view of the above points, and the VRAM update time is lengthened due to a large amount of update of display data due to scroll display of a display image, and the display screen itself has a memory property. Power saving that solves the problem of lengthening the update time of the display image itself that occurs in the case of such a display device and can rewrite the display content at high speed even when using a ferroelectric liquid crystal An object of the present invention is to provide a highly effective display device and a screen display control method.

[0026]

In order to achieve the above object, the present invention is configured as follows. That is, first, in a display device that displays an image based on display data on the image display means, an image based on the given display data is displayed within a predetermined partial area of the image display means in the scroll display mode. It is characterized by comprising means for controlling.

Secondly, in a display device in which the display screen itself has a memory property, or in a display device having means for temporarily holding a display image systematically, an image based on given display data is displayed in the scroll display mode. It is characterized in that it is provided with means for controlling to display within a predetermined partial area of the image display means.

Furthermore, in the second configuration, the image display means has a structure in which a plurality of cells for display are arranged in a matrix, and each cell is driven by a display device drive circuit which operates in cell units according to display data. The display device drive circuit can drive an area to be driven by dividing the area, and when the image is scroll-displayed on a part of the display screen of the image display means, the display target area is It is characterized in that it is controlled so as to be driven as a drive target.

Further, in the display device for displaying the image of the display data on the image display means, the holding means for temporarily holding the data of the display image, and the given display data, in the scroll display mode, the predetermined value of the image display means. In order to display the image within the partial area of the holding means, update holding control is performed in the predetermined partial area of the holding means, and control means for reading the data of the holding means and providing the image display is provided, the control means When performing scroll display on a part of the display screen, while updating the data only in the area corresponding to a part of the display screen in the holding means,
Other parts are not updated, or are provided with a control function to reduce the number of updates compared to the normal display.

When a scroll display is performed on a part of the display screen, as a result of scrolling, display data of an image obtained by thinning out pixels of the original display image to be newly displayed is transmitted from the display signal source. , And display data.

According to the present invention, the VRAM update time is lengthened due to a large amount of update of display data due to scroll display of the display image, and the display image generated when the display screen itself has a memory property. In the scroll mode of the display image, the problem that the update time of the image itself is lengthened is transmitted, and the data in which the pixels are roughened is transmitted, and by using this data, a part of the display screen of the image display means is used to display the image. The scroll display reduces the data transmission time and image display control time, shortens the time required for the user to retrieve the image information, and provides a comfortable user interface as well as providing the image information. During the scrolling, by transmitting a display image less than the display data of the full screen of the display device and performing display signal processing, As a whole Temu, it is possible to provide a display device with low power consumption.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Specific Example) Hereinafter, a specific example of the present invention will be described. FIG. 1 is a block diagram of a liquid crystal display device according to a first example of the present invention. FIG. 1 shows a normal liquid crystal display device having a function of inputting a scroll ON signal 15 as scroll information.

In FIG. 1, 1 is a connector, 2 is a display controller, 3 is a DC / DC converter, 4 is a liquid crystal cell driving voltage source, 5 is an upper X driver, 6 is a lower X driver, 7 is a Y driver, and 8 Is a liquid crystal panel. Also, 9
Is display data, 11 is an upper signal line (X) driver cell drive voltage, 13 is a lower signal line (X) driver cell drive voltage, 10 is a display signal corresponding to the upper X driver 5, 1
2 is a display signal corresponding to the lower X driver 6, 14 is a signal for controlling the Y driver 7 that scans the liquid crystal panel 8, and 15
Is a scroll ON signal, and 16 is a drive circuit control scroll ON signal.

The DC / DC converter 3 is a DC-DC converter which converts a DC voltage supplied from a DC power source (battery or the like) into a required voltage level and outputs it. The voltage source 4 obtains a voltage required for driving the liquid crystal cell from the converted output of the DC / DC converter 3.

The liquid crystal panel 8 is a display panel using a liquid crystal, and is a panel for a two-dimensional display in which a plurality of cells having a small area are arranged in a matrix so that each cell can be individually driven. Is. Since the liquid crystal panel 8 has cells arranged in a matrix,
By selectively driving the row direction (Y direction) and the column direction (X direction) and controlling the driving, it is possible to control ON / OFF of a specific cell.

The upper X driver 5 and the lower X driver 6 are
A driver for driving the liquid crystal panel 8 in the column direction (X direction), and because of the wiring that can be applied to the liquid crystal panel 8, the X of the cell in the upper region of the liquid crystal panel 8 is considered.
It is divided into an upper X driver 5 for directional driving and a lower X driver 6 for driving cells in the lower region of the liquid crystal panel 8 in the X direction. The Y driver 7 is a driver for driving the liquid crystal panel 8 in the Y direction.

The display controller 2 is based on the display data and the scroll ON signal given via the connector 1,
A signal is generated to display an image corresponding to the display data and is given to the upper X driver 5, the lower X driver 6, and the Y driver 7, and these drivers generate a liquid crystal drive signal according to the given signal and respond. It is given to each cell that does. Display data and scroll ON signal are the display controller (D
ISP-CONT), usually D
Since the ISP-CONT has a mechanism that generates a scroll ON signal for notifying it in the scroll mode, this system determines whether or not the scroll mode is on the basis of the scroll ON signal obtained from the DISP-CONT. As is known, in the scroll mode, only a specific narrow area of the display area of the liquid crystal panel 8 is driven to control the image display of this area.

Further, in this specific example, in order to enable a smooth and fast scroll operation at the time of scroll display in which the speed of screen display is particularly concerned, if the display data is a character, the font is thinned, If it is an image, it is applied to the liquid crystal display device of FIG. 1 together with a scroll ON signal indicating that scroll display is performed after the process of thinning pixels is performed on the system side, thereby shortening the data transmission time, while the display device side With the use of the fact that the amount of data to be displayed is small and the apparent operation speed is increased by narrowing the area used for scroll display, a comfortable scroll operation is realized by these synergistic effects.

Therefore, in this example, in the case of scroll display, the scroll display area is a partial area of the display screen of the display device as shown in FIG. This is to thin out the data of the image to be used for display so that the display image fits within this partial area. For example, the image is roughened to about 1/16 of the entire display screen. As a result, the number of image data for frame writing is drastically reduced and the display data transmitted from the system side to the liquid crystal display device can be performed in a short time. Is performed so that the rewriting time can be shortened and the power consumption of the liquid crystal display device is also reduced.

The peripheral structure of the liquid crystal panel 8 of the liquid crystal display device shown in FIG. 1 is as shown in FIG.
Each of the Y driver 7 and the Y driver 7 has a configuration in which four sets of drive circuits DRV are serially connected, and each drive circuit DRV is 1 in the row direction or the column direction of the liquid crystal panel 8.
It is responsible for driving / 4.

The drive circuit DRV has a start pulse (S
When TH, STV are given, clock signals (CPH,
CPV) and display data will be fetched in sequence.
When the display data is captured, a data capture pulse is generated and passed to the next stage.

Therefore, the drive circuit DRV has a start pulse input terminal and a data capture pulse output terminal, and the front and rear drive circuits DRV use the data capture pulse output terminals of the front drive circuit DRV and the rear drive circuit. The configuration is such that it is connected to the DRV start pulse input terminal.

Then, the data capture pulse output terminal of the drive circuit DRV of the first stage and the drive circuit DR of the next stage
A two-input AND gate (51, or 61, or 71) is provided between the start pulse input terminal of V, the inverted signal of the scroll ON signal is input to one of the input terminals, and the other terminal is connected to the first stage. By connecting to the data capture pulse output terminal of the drive circuit DRV, scroll
When the N signal is present, the data acquisition pulse of the drive circuit DRV of the first stage is not passed to the drive circuit DRV of the next stage.

In this circuit example, the scroll ON signal is inverted for each driver, that is, the X drivers 5, 6 and the Y driver 7, and each two-input AND gate (51, 51).
or 61, or 71), and when there is no scroll ON signal, the first stage drive circuit DR
V data capture pulse is the drive circuit DRV of the next stage
However, when there is a scroll ON signal, the data capture pulse of the drive circuit DRV of the first stage is not passed to the drive circuit DRV of the next stage.

Therefore, when there is no scroll ON signal, the X drivers 5, 6 and the Y driver 7 operate so that the normal display is performed. However, by inputting the scroll ON signal, the display controller 2 controls the scroll display. When the drive circuit control scroll ON signal 16 which is a signal is output, both the X drivers 5 and 6 and the Y driver 7 operate so that only the drive circuit in the first stage operates normally and the other drive circuits do not operate.

Therefore, when the scroll ON signal is given, only a (1/4) × (1/4) total 1/16 area is accessed by the pair of row and column drive circuits DRV. be able to.

In the configuration shown in FIG. 2, when the scroll ON signal is input, only the first-stage drive circuit DRV of the row-direction and column-direction drivers operates, and the first-stage drive circuit DRV can be driven. LCD panel 8
The scroll image can be displayed in a 1/16 area (the first section among the areas obtained by equally dividing the display screen of the liquid crystal panel 8 into 16 sections).

Next, the operation of the present apparatus having the above configuration will be described. The liquid crystal display device having such a structure has a structure in which the display data 9 is input from the system side through the connector 1 and the scroll ON signal 15 is input through the connector 1 when a scroll operation is performed.

The display data 9 input from the system side is input to the display controller 2, where it is distributed to the display signals 10 and 12 corresponding to the upper X driver 5 and the lower X driver 6, and this display controller 2 is further distributed.
At 14, a signal 14 for controlling the Y driver 7 for scanning the liquid crystal panel 8 is generated. Then, the Y driver 7 is driven in the Y direction of the liquid crystal panel 8 while switching the position in the Y direction while timing control is performed by the signal 14, and the upper X driver 5 and the lower X driver 6 respectively display signals 10 corresponding to each other. , 12 to output a voltage corresponding to the signal and drive the liquid crystal panel 8 in the X direction.

In this way, the Y driver 7 performs scanning in the Y direction and the X drivers 5 and 6 perform drive control by applying a voltage corresponding to the display signal in the X direction, whereby the liquid crystal panel 8 corresponds to the display data. The image will be displayed.

Next, it is assumed that a scroll operation is performed on the system side and a scroll ON signal 15 is input to the liquid crystal display device from the system side. Then, the scroll ON signal 15 causes the display controller 2 to generate a drive circuit control scroll ON signal 16 which is a driver control signal for setting the X drivers 5 and 6 and the Y driver 7 in the scroll mode, and these respective drivers are generated. Input in 5, 6, 7.

X drivers 5, 6 and Y driver 7
In each case, the drive circuit DRV has a four-stage configuration, and the drive circuit DRV has start pulses (STH, STV).
Is applied, the display data is sequentially captured in synchronization with the clock signals (CPH, CPV), and when the display data is captured, a data capture pulse is generated and passed to the next stage.

Therefore, the drive circuit DRV has a start pulse input terminal and a data capture pulse output terminal, and the front and rear drive circuits DRV use the data capture pulse output terminals of the front drive circuit DRV and the rear drive circuit, respectively. The configuration is such that the start pulse input terminal of the DRV is connected, and there is 2 between the data capture pulse output terminal of the first stage drive circuit DRV and the start pulse input terminal of the next stage drive circuit DRV.
An input AND gate (51, or 61, or 71) is provided, an inverted signal of the scroll ON signal is input to one of its input terminals, and the other terminal is connected to the drive circuit DRV of the first stage.
By connecting to the data capture pulse output terminal of the first drive circuit DR when there is a scroll ON signal
V data capture pulse to drive circuit DRV of the next stage
It is configured so that it is not passed to.

Then, the scroll ON signal is inverted for each driver, that is, the X drivers 5, 6 and the Y driver 7, and each two-input AND gate (51, or 61, o).
r71), scroll ON
When there is no signal, the data capture pulse of the drive circuit DRV of the first stage is passed to the drive circuit DRV of the next stage, but when there is a scroll ON signal, the data capture pulse of the drive circuit DRV of the first stage is not passed to the drive circuit DRV of the next stage. It is designed to do so.

Therefore, when there is no scroll ON signal, the X drivers 5, 6 and the Y driver 7 operate so that the normal display is performed, but when the scroll ON signal is input, the scroll display is made from the display controller 2. When the drive circuit control scroll ON signal 16 which is the control signal at the time is output, both the X drivers 5 and 6 and the Y driver 7 are normally operated only in the first stage drive circuit,
The other drive circuits operate so as not to operate.

That is, in the normal operation, the start pulse STH (U) for the row direction is input to the upper X driver 5 in synchronization with the first display signal of the display signal V _sig (U) 10, and the first stage The display data is sequentially fetched from the drive circuit DRV of No. 1, and when the drive circuit DRV of the first stage finishes fetching the display data 10, the data fetch pulse 50 is outputted to the next stage, and the data fetch pulse 50
Accordingly, the drive circuit DRV at the next stage starts taking in the display data 10.

However, when the drive circuit control scroll ON signal 16 which is a control signal during scroll display is applied to the X drivers 5 and 6, the data fetch pulses 50 and 60 output from the first stage to the next stage are changed. AND gate 5
Therefore, it is possible to achieve a state in which only the first stages of the X drivers 5 and 6 operate and the subsequent stages do not operate during scroll display. Similarly, in the case of the Y driver 7, it is possible to achieve a state in which the scan start pulse transmitted to the next stage during scroll display is operated only by the first stage of the Y driver 7 by the AND gate 71 and the subsequent stages are not operated.

Therefore, when the liquid crystal panel 8 is constructed by using a material having a memory property for the liquid crystal cell, the display data is sequentially displayed only by the first stage portions of the X drivers 5 and 6 and the first stage portion of the Y driver 7. However, since the other display screen portions are not driven at all, the screen of the region which is not driven at all retains the image before the scroll display because of the memory property. The display state is shown in FIG.

In the scroll display, if the display data is characters, the font is thinned out, and if it is an image, pixels are thinned out on the system side and then transmitted to the display device side, and the number of dots of the display image is small. . By this thinning,
The number of pixels in each of the X and Y directions per screen is 1/4
, The number of pixels is 1/16 of the original screen.
6 is driven for display drive only by the drive circuit DRV in the first stage, and the Y driver 7 scans in the Y direction in the range of ¼ in the Y direction. As shown in FIG. In this case, the image is displayed in the display range of 1/16 of the entire display screen of the liquid crystal panel 8. This display screen is rough by thinning out the pixels of the original image, but the scroll screen only needs to have a quality enough to grasp the state, and there is no usage to see the contents in detail during scrolling, This is sufficient for practical use. Since one screen of image is displayed in the display range of 1/16 of the entire display screen of the liquid crystal panel 8, the time required for display operation is also 1/16.

On the other hand, since it is necessary to write each frame only to about 1/16 of the entire display screen of the liquid crystal panel 8, the display data transmitted from the system side to the liquid crystal display device is reduced to 1/16. be able to. Therefore, the data transmission time can be reduced to 1/16 by simple calculation, and since the writing operation is performed only on a part of the screen, the power consumption of the liquid crystal display device is naturally 1/4. It can be reduced to:

Therefore, the display at the time of scrolling can be performed at high speed and smoothly, and power saving can be achieved. Details of transmitting display data from the system side to the display device side will be described later.

In the present invention, when scroll display is performed, the scroll image is displayed on a part of the screen of the liquid crystal panel 8. The display screen in the scrolling state is one in which pixels are thinned out, and is performed by a display signal in which a part of the display signal to be displayed while being scrolled in a window in the screen is thinned out (subsampled). . That is, in the case of characters due to thinning, the font becomes rough, which is sufficient for determining the composition of the entire sentence, but is insufficient for reading character by character. Also, in the case of a picture, it will be enough to understand the rough appearance.

However, in the case of normal scroll display, if the target is a document file, it is sufficient to know the paragraph breaks of a sentence, the presence or absence of figures and tables, and page transitions rather than the content of a sentence. That is, the layout information of the sentence is more important than the content of the sentence. Further, when searching media such as a database, it suffices to quickly find the desired one from the acquired information.

Therefore, in order to find a desired sentence or information at high speed, it is important to search media such as a database and transfer data at high speed, but similarly, the scroll screen of the display device itself is displayed at high speed. Need to do.

Therefore, in order to achieve the object, it is important to display an image in which a layout of a sentence can be discriminated in a small size on the screen and rewrite the contents at high speed. In particular, in the case of a liquid crystal display device using a ferroelectric liquid crystal that requires a long time to update the entire screen, scroll information can be rewritten at high speed, and the effect of enabling comfortable scroll operation is practically Extremely large.

Here, the drive signal will be described by taking a ferroelectric liquid crystal (FLC) as an example of the liquid crystal having a memory property. FIG. 4 shows the relationship between the applied voltage of FLC and the amount of transmitted light.
As shown in FIG. 4, in the case of FLC, the applied voltage is 0 [V].
Even in the case of, that is, the stable state is set in either the ON state or the OFF state even when the driving is not performed, it is understood that a liquid crystal display having a memory property can be realized.

When driving this FLC, in order to turn it on, a voltage value exceeding + Vth and further exceeding + Vsat is applied to the liquid crystal cell, and then a drive signal for returning to 0 [V] is applied to the liquid crystal cell. It may be applied.

To turn it off, a voltage value exceeding -Vth and further exceeding -Vsat is applied to the liquid crystal cell, and then a driving signal for returning to 0 [V] is applied to the liquid crystal cell. It may be applied. FIG. 5 shows an example of drive waveforms for driving the FLC. The driving of FIG. 5 is an example of a driving method in which writing in the ON state and writing in the OFF state are repeated for each field to form one frame with two fields. Within one frame, the drive signal on the scanning side has a phase of 18 in the first and second fields.
It consists of signals that differ by 0 degrees.

In the driving example of FIG. 5, in order to display in the OFF state, the scanning electrode (a) is applied when a negative voltage is applied in the latter half of one scanning time, and the scanning electrode is applied. By applying the OFF writing pulse (b) whose phase is 180 degrees different from that of the signal on the side from the signal line side, the voltage applied to the pixel returns to 0 [V] after exceeding -Vsat (d). A stable state in the OFF state can be obtained.

Further, in order to display the ON state, O
Contrary to the FF state writing, in a field to which a scanning signal (a) such that a positive voltage is applied in the latter half of one scanning time is applied, an ON state writing pulse (c ) Is applied to the signal line side, the voltage applied to the pixel exceeds 0V after exceeding + Vsat.
Since it returns to [V], a stable state in the ON state can be obtained.

As described above, it is possible to write the OFF state and the ON state to the FLC. In the case of the FLC liquid crystal display device as shown in FIGS. 1 and 2, the X drivers 5 and 6 are ON or OFF. Writing pulse is generated, and the Y driver 7 generates a scanning signal. The signal voltage at that time is the voltage source 4 for driving the liquid crystal cell.
Created in.

Here, considering the signal voltage (driving waveform) applied to the pixel which is not driven, the field after writing the OFF state and the state before writing the ON state in FIG. As can be seen by focusing on the field, it is sufficient to apply a signal that does not exceed + Vth or -Vth in the same phase as the signal applied to the scan electrodes. By doing so, the voltage applied to the pixel is 0
Since it changes in the vicinity of [V], it does not change from the ON state or the OFF state shown in FIG.

Next, FIG. 6 shows a configuration example of the system side for supplying the display data 9 to the liquid crystal display device as shown in FIGS. In the figure, 100 is the display device of the present invention having the configuration described in FIGS. 1 and 2, and 15 is scroll ON information. Others are the same as the system configuration of the conventional personal computer described with reference to FIG. 8, and the same components are denoted by the same reference numerals and description thereof is omitted.

In the example shown in FIG. 6, the scroll ON signal 15 is supplied from the display controller (DISP-CONT) 80 to the display device 100. In the case of scrolling, the display data is obtained by thinning out pixels and DI.
The point given to SP-CONT80 is a part greatly different from the normal system.

However, the DISP-CONT 80 is in an operation mode in which scroll display is performed when a scroll mode is instructed on the system side, but it is usually configured to output scroll information at that time. Therefore, the scroll ON signal 15 can be supplied to the display device 100 by using the scroll information as it is.

Normally, when there is cursor key input information or scroll key input information from the keyboard or mouse, the system (operating system: OS) sends the image memory (VRAM) 82 to the DISP-CONT 80. Specify the scroll start address or scroll end address of. That is, the system (OS) specifies the scroll address and the VRAM 8
While the contents of 2 are being updated, the scroll is in the ON state.

Therefore, for the display device, the OS is DI
After the scroll start address is designated for the SP-CONT 80 and the VRAM 82 is updated, it is determined that the scroll is on until the scroll address is released,
The scroll ON signal 15 may be supplied to the display device.

Here, the flow of system-like processing will be described. FIG. 10 is a flowchart showing an example of a series of processes in the scroll mode. Hereinafter, description will be made with reference to this flowchart.

First, when the system user operates the mouse, cursor keys, etc. to instruct scrolling of the display screen, the normal mode that has been performed up to that point, that is, the mode of full screen access of the display screen and VRAM 82,
The display processing is changed to the scroll mode display processing as shown in FIG.

In the scroll mode processing, the CPU 84 first refers to the address of the SAM (Serial Accece Memory) that has been read from the VRAM 82 up to that point, and the SAM address at which scrolling starts and the SAM address at which scrolling ends. And are calculated (S in FIG. 10)
1).

The calculated address is set in the display controller (DSP-CONT) 80, and the DSP-CONT 80 is set in the scroll mode (S2 in FIG. 10).

Next, the data to be displayed is the work RAM.
If it is necessary to read the additional data, the necessary data is read from the target medium (S in FIG. 10).
3, S13, S14). For example, currently, work RAM 8
When the last data stored in 6 is accessed (displayed) and the sentence following the part is desired to be displayed, it is necessary to read new data from the medium.

When the data reading from the target medium is completed, it is determined whether the data transmitted from the work RAM 86 to the VRAM 82 is a character or an image (S4 and S5 in FIG. 10).

As a result of the judgment, when the data to be displayed is a character, the character code is converted into a character font (information on the dot configuration for actually displaying as an image) (S6 in FIG. 10). For conversion to this font, a font such as a kanji ROM or application software executed on the system is used.

The characters changed to the font are VRAM8
2 is transmitted (S8 in FIG. 10), but since the font information is thinned and transmitted during the transmission, the character font data transmission is completed in less time than in the normal case.

If the result of the determination in S5 of FIG. 10 is that it is an image, the image data in the work RAM 86 and the like is subsampled and read, and is further transmitted to the VRAM 82 (S8 in FIG. 10). Since the image information is thinned and transmitted during the transmission, the image data transmission is completed in less time than in the normal case.

Next, the image data stored in the work RAM 86 is thinned out and transmitted to the VRAM 82. VRA
Writing to M82 increments (+1) the address for 1 byte of display data that is normally transmitted in the column direction of the VRAM address, but when the row address is accessed by a fraction of the column address. , Is incremented (+1).

For example, when thinning the displayed data to 1/16, both the horizontal and vertical directions of the display screen are reduced to 1/4.
It can be realized by thinning out each. Therefore, the column address corresponding to the horizontal direction of the display screen is 1/4 of all column addresses.
When it reaches, the row address is incremented by 1 and the column address is reset to "0".

Similarly, the row address is also 1 / of all the row addresses.
When 4 is accessed, it is reset to the first address. Of course, the timing of resetting the column and row addresses of the VRAM 82 differs depending on how many thinning intervals are set, but this is not particularly limited as long as it matches the display being used. Absent.

In this way, the display data is stored in the VRAM 8
Only a part of 2 is written, and the scroll mode is realized. Updating of one screen is realized on the screen in which writing to the VRAM 82 is thinned.

In the screen where the writing to the VRAM 82 is thinned out, when the updating for one screen is completed,
It is confirmed whether or not the scroll display request from the user is continuing (S9 in FIG. 10). As a result, if the scroll request is continuing, the process returns to step S1 and again.
The process from setting the scroll address is repeated.

When the scroll request from the user disappears after a certain thinning screen is updated (S9 in FIG. 10), the scroll address is fixed and the address is set as a normal read address (S10 in FIG. 10). . Therefore,
The state of the address at the end of scrolling is set to the read start address and end address in normal display, and the scroll mode of DISP-CONT 80 is reset (S11 in FIG. 10).

Next, after writing the latest data of the work RAM 86 to the entire display area of the VRAM 82 and updating the entire screen (S12 in FIG. 10), the normal display mode is returned to. Regarding transmission of display data between the system and the display device 100, as shown in FIGS. 1 and 2, in the display device 100 using FLC, only a part of the screen is updated for each frame when scrolling. In the system, the display data may be transmitted to the display device by sub-sampling the display data according to the display size.

FIG. 7 shows the read data (a) during normal display.
And an array of read data (b) during scroll display. At the time of normal reading, the data in the i-th row and the j-th column is G
From 1, 1 to Gi, j are read out in order, but since display data of each frame is displayed only on a part of the screen of the display device during scroll display, G1, 1 G1, 5 ... (Column direction) and G5 , 1 G9,1 (row direction) may be thinned out and the display data may be transmitted.

By doing so, it becomes possible to transmit the required amount of display data in the scroll display, and it is possible to suppress an increase in extra power consumption required for transmitting the display signal.

As described above, the scroll state can be displayed on a part of the display screen of the display device after the scroll state is detected by the system. By doing so, it is possible to suppress the update data amount of the scroll display device contents, and it is possible to reduce the update time of the display screen and the power consumption required for updating the display contents.

Up to now, the description has been made in the case of the display device having a memory property on the display screen such as the FLC liquid crystal display device, but the display image displayed at a constant cycle such as the CRT should be refreshed. If this does not happen, high-speed scroll display can be realized by supporting the system side.

That is, in order to display the scrolling state as shown in FIG. 7B, a fraction of the display image originally necessary is displayed.
Therefore, the update time of the VRAM itself can be shortened by thinning the update data of the VRAM held by the system to the data amount corresponding to the scroll status display screen from the beginning, and updating the data. The scroll time for the entire system can be shortened.

For example, in the system as shown in FIG.
If you want to check the text on the floppy disk while scrolling, check the FDC 88, work RAM 85, D from the CPU 84.
After the mode is set to ISP-CONT80 etc., FD
Data is transmitted from the C88 to the RAM 86 and the VRAM 82, but at that time, the transmission data to the VRAM 82 can be reduced to a fraction of that of the normal case, so naturally the data transmission time of the entire scroll operation is shortened, and as a result, As a result, the speed of the entire system can be increased.

As described above, according to the present invention, the scroll mode detection in the system, the scroll state display using a part of the display screen in the display device, or the V of the system itself is performed.
By reducing the amount of RAM update data, it is possible to realize a high-speed screen update at the time of scrolling, and provide an environment in which the user can comfortably search for a required sentence. In that case, it also has a feature that the power consumption required for updating the display data can be reduced.

Further, the present invention relates to a display device having a scroll information display method, and if the display device or system has a display memory (memory property of the display itself), a CRT, LCD, PDP.
It is widely applicable to (plasma display panel), magnetic display, mechanical display, etc., and is not limited by the display material or the like.

(Second Specific Example) FIG. 11 is a block diagram of a liquid crystal display device according to a second specific example of the present invention. FIG.
The liquid crystal display device of No. 1 is an example in which a normal TN liquid crystal is used. Although TN liquid crystal is the most used liquid crystal material at present, it has no memory property. That is, in the example of the block diagram shown in FIG. 11, when the scroll display is performed using the material having no memory property, the power consumed by the liquid crystal display device is the same as that of the liquid crystal display device using the liquid crystal material having memory property. An example of a configuration that can reduce the above is shown.

The operation will be described below with reference to FIG. Basically, an n frame counter 280 and an AND gate 281 are added to the liquid crystal display device having the configuration shown in FIG.

The n-frame counter 280 counts the CPV signal, which is the vertical synchronizing signal applied at the beginning of one frame.
It is a circuit that generates the FRM_ON signal that turns on the AND gate 281 only during the frame time. Therefore, Y
AND gate 7 controlling the second and subsequent stages of driver 7
1 turns on only once every n frames while the drive circuit control scroll ON signal 16 is on.

That is, when scrolling, the liquid crystal panel 8
Is rewritten (refreshed) once every n frames. V on the system side when scrolling
Since the RAM 82 is updated only partially, it is wasteful to rewrite the data that is not updated in the VRAM 82 every frame in the liquid crystal display device 100. However, since the TN liquid crystal itself has no memory property, it cannot be performed without complete refreshment.

Therefore, the circuit for realizing refresh in each frame, no refresh at the time of scrolling, and an intermediate state thereof are the circuits of FIG. That is, after writing a signal to the liquid crystal panel 8 used in the liquid crystal display device, before the signal leaks (discharges) from the liquid crystal panel 8 and the liquid crystal image is deteriorated, the signal is again supplied to the cell of the liquid crystal panel 8. By writing, it is possible to reduce the power consumed by the liquid crystal display device without deterioration of the display image even with a liquid crystal material having no memory property.

By this, the power consumption can be reduced,
That is, n in the following equation depends on the liquid crystal material used,
By changing n, it is possible to reduce power consumption up to the ratio of ((n-1) / 4) +1) / n. General TN
According to the combination of the liquid crystal and the TFT, n can be reduced to about 3 to 10, that is, the power consumption can be reduced to about 1/2 to 1/3. Although this reduction rate does not reach that of the ferroelectric liquid crystal having a memory property, the combination of the TN liquid crystal and the TFT can realize low power consumption in a display having a halftone or a full color display.

The above is a specific example of the case where the liquid crystal display device is used for a display, but with the configuration shown in FIG. 1, similar low power consumption or the same effect can be expected. For example, in a PDP (plasma display panel), the power consumption can be reduced by lowering the refresh rate for the display area where scrolling is not performed. Further, in the PDP, by using preliminary discharge for display instead of display, it is possible to sustain the discharge required for display, and it is possible to increase n. In that case, a larger reduction in power consumption can be expected.

Although various concrete examples have been described above, in short, the present invention lengthens the VRAM update time due to a large amount of update of display data due to scroll display of a display image, and the display screen itself has a memory property. The problem of increasing the update time of the display image itself, which occurs in the case of a display device having such a display device, transmits data with coarse pixels in the scroll mode of the display image, and displays the image in the image display means by this data. By using a partial area of the screen to scroll the image, the data transmission time and the image display control time are shortened, and the time required for the user to retrieve the necessary image information is shortened, making it more comfortable. User interface, and transmits less display image than the display data of the full screen of the display while scrolling image information. And by performing a display signal processing, as a whole system, in which can provide a display device with low power consumption.

[0110]

As described above, according to the present invention, the VRAM update time is lengthened due to a large amount of update of display data due to scroll display of display images, and the display screen itself has a memory property. It solves the problem of a long update time of the display image itself in the case of a display device and provides a comfortable user interface, while displaying image data on the full screen of the display device while scrolling image information. By transmitting fewer display images and performing display signal processing, a display device with low power consumption can be obtained as the entire system.

[Brief description of drawings]

FIG. 1 is a block diagram of a liquid crystal display device according to a specific example of the present invention.

FIG. 2 is a detailed block diagram around a liquid crystal cell according to a specific example of the present invention.

FIG. 3 is a diagram for explaining a display screen in a scroll state.

FIG. 4 is a diagram showing an applied voltage and a light transmission amount of a ferroelectric liquid crystal.

FIG. 5 is a diagram showing an example of a drive waveform of a ferroelectric liquid crystal.

FIG. 6 is a block diagram showing a configuration example of a system (personal computer) according to a specific example of the present invention.

FIG. 7 is a diagram showing a display data array for explaining transfer of display data.

FIG. 8 is a block diagram showing a configuration example of a conventional system (personal computer).

FIG. 9 is a diagram showing a configuration example of a VRAM.

FIG. 10 is a diagram for explaining the present invention and is a flowchart for explaining processing of the system in a scroll mode.

FIG. 11 is a diagram for explaining the present invention and is a block diagram of a liquid crystal display device according to a second example of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Signal input connector of display device 2 ... Display controller 3 ... DC / DC converter 4 ... Liquid crystal cell driving voltage source 5 ... Upper signal line (X) driver 6 ... Lower signal line (X) driver 7 ... Scanning signal line (Y) Driver 8 ... Liquid crystal cell 9 ... Display data 10 ... Upper signal line (X) driver display data 11 ... Upper signal line (X) driver cell drive voltage 12 ... Lower signal line (X) driver display data 13 ... Lower signal line (X) driver cell drive voltage 14 ... Scan signal line (Y) driver scan control signal 15 ... Scroll ON signal 16 ... Drive circuit control scroll ON signal 50, 60 ... X driver data acquisition Pulse 51, 61 ... AN for data acquisition pulse of X driver
D gate 70 ... Y driver data capture pulse 71 ... Y driver data capture pulse AND gate 80 ... Display controller (DISP-CON
T) 82 ... Image memory (VRAM) 84 ... CPU 86 ... Working RAM 100 ... Display device 280 ... N frame counter 281 ... AND gate.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location G09G 5/34 9377-5H G09G 5/34 W

Claims (6)

[Claims] 1. A display device for displaying an image based on display data on an image display means, wherein an image based on given display data is controlled to be displayed within a predetermined partial area of the image display means in a scroll display mode. A display device comprising means. 2. A display device in which the display screen itself has a memory property, or a display device having a means for temporarily holding a display image systematically, wherein an image based on given display data is displayed in a scroll display mode. A display device, comprising means for controlling to display within a predetermined partial area of. 3. The image display means has a structure in which a plurality of cells for display are arranged in a matrix, and each cell is driven by a display device drive circuit which is performed in cell units according to display data, and the display device drive circuit is driven. The target area can be divided and driven in units of each divided area, and when an image is scroll-displayed on a part of the display screen of the image display means, control is performed to drive the display target area as a drive target. The display device according to claim 2, wherein: 4. A display device for displaying an image based on display data on an image display means, holding means for temporarily holding display image data, and predetermined display data for the given display data in a scroll display mode. Display unit, which controls updating and holding in the predetermined partial area of the holding means so as to display in the partial area, and controls the data of the holding means to be read out for image display. . 5. A display device for displaying an image based on display data on an image display means, wherein an image based on given display data is controlled to be displayed within a predetermined partial area of the image display means in the scroll display mode. A screen display control method characterized by the above. 6. A display device for displaying an image based on display data on an image display means, when the scroll display is performed, the display data of the scroll display target is thinned, and the image based on the thinned display data is displayed in a predetermined manner on the image display means. A display control method for a screen, characterized by controlling to display in a partial area.